Thermoformed containers are relatively inexpensive to produce. However they have the disadvantages that they are difficult to fill and are not recloseable with a good seal. The latter is a distinct disadvantage when the contents of the thermoformed containers are not to be used at one time. When the product is to be dispensed in two or more portions a container must be resealable. Also the reseal feature must be a leakproof seal. This is difficult to do in view of the fact that thermoformed containers usually have thin walls. When container walls are thin and flex it is difficult to get a good seal. This is particularly the case where the walls in the area of the seal and reseal feature are thin and flex.
The prior art with regard to recloseable thermoformed containers is described in U.S. Pat. No. 3,278,085; U.S. Pat. No. 3,913,734; U.S. Pat. No. 4,209,096 and U.S. Pat. No. 5,228,782. U.S. Pat. No. 3,278,085 discloses a sachet container that is opened by removing a tear-off portion to open a nozzle. The nozzle is closed by folding over the top part of the nozzle with the folded portion held by two locking tabs.
In U.S. Pat. No. 3,913,734, the container is of the blister pack type with the backing board having a memory of its original position. The nozzle of the container is opened by bending backward the backing board. When some of the contents have been dispensed, the backing board regains its original shape closing the container. This container is improved upon in U.S. Pat. No. 4,209,906. In this patent, there is added a securing means to assure that the backing board acquires its original position and retains its original position.
U.S. Pat. No. 5,228,782 discloses another fold-over type of recloseable sachet. The nozzle is opened by the removal of a tear-off tab. The sachet is closed and locked by folding over a nozzle at an angle and inserting the end of the nozzle into a holding slit.
A locking technique of using an interfitting projection and aperture is disclosed in EP 18,118A. This can be used to secure a folded over portion to a main portion of a container.
None of these references discloses an effective recloseable feature for a thermoformed container. Further none of these thermoformed containers have an effective leakproof resealable feature, and clearly not a resealable feature which can take mishandling.
The thermoformed containers of the present invention solve the problem of providing thermoformed containers with recloseable closures where the closure will provide leakproof seals when reapplied to the thermoformed container. This thermoformed container can be used in instances where a liquid or solid is to dispensed in multiple doses over a period of time.